The present invention relates to an apparatus for and method of attaching a lens holder to an uncut lens for a spectacle lens. More particularly, the lens holder of the present invention comprises a jig attached to an uncut lens and is used as a central axis of rotation for the uncut lens in a process for grinding the edge of an uncut lens.
Typically, a spectacle glass is prepared first by processing an uncut spectacle lens (in general, a so-called round lens having a circular shape) into a shape to fit the shape of a spectacle frame, and then by fitting the cut lens into the spectacle frame. For such preparation of the spectacle glass, a layout must be conducted. A layout includes deciding the position of the optical center based on prescription data of the eye of the person who wears the spectacle glass (the dioptric power, the cylindrical dioptric power, the distance between the right and left eyes and other such data) and the spectacle frame shape data which depends on the type of frame selected by the person who wears the spectacle glass. The layout is conducted essentially by bringing the optical center (in the case of a single vision lens) or the eyepoint (in the case of a multifocal lens) of the spectacle lens in line with the position of the pupil center of the person who wears the spectacle glass when the prepared spectacle glass is worn by the person.
In general, when a person wears a spectacle glass having a spectacle frame selected by the person, it is rather rare that the geometrical center, with regard to the shape of the spectacle frame, and the pupil center of the person are at the same position on the lens. Moreover, when processing an uncut lens into a shape to fit the selected frame, the geometrical center of the shape formed by the processing (the shape of the spectacle frame) is typically brought in line with the position of the optical center of the lens. In other words, the uncut lens is processed so that these two positions are one and the same. As a result, a problem arises in that when worn, the wearer""s pupil center is not placed in line with either the position of the optical center (or the eyepoint) of the spectacle lens once the spectacle glass is completed by fitting the processed lens into the spectacle frame to be worn. It is therefore necessary that the optical center (or the eyepoint as the case may be moved from the position of the geometrical center and brought in line with the position of the pupil center.
When the layout is complete, an uncut lens (a prescribed lens) which satisfies the conditions for the above layout and prescription for the wearer and is suitable for processing is selected and processed. Processing of the uncut lens is conducted by using an apparatus for processing a lens which grinds edge portions of the uncut lens by a grinder or a cutter while the uncut lens is rotated around a specific axis approximately perpendicular to the optical face of the uncut lens. To process the uncut lens by the apparatus for processing a lens, a lens holder comprising a jig is used as the rotational center axis of the uncut lens and is attached to the uncut lens in advance.
Heretofore, the lens holder is attached at the position of the optical center in the case of a single-vision lens. In the case of a progressive multifocal lens or a multifocal lens (in general, a bifocal lens), the lens holder is attached at the position of the eyepoint of the lens. One example of an apparatus for attaching the lens holder at the position of the eyepoint, is the apparatus described in Japanese Patent Application Laid-Open No. Heisei 11(1999)-216650, hereby incorporated herein by reference.
When the apparatus described in Japanese Patent Application Laid-Open No. Heisei 11(1999)-216650 is used, images of hidden marks are observed by projecting an image of an uncut lens onto a screen and the position of the eyepoint is obtained from the positions of the hidden marks. Then, the position of the uncut lens is decided by moving the uncut lens so that the eyepoint is brought to the position of the center of a cross reticle on the screen showing the reference position of the apparatus for attaching a lens holder, and the lens holder is attached at the decided position.
However, it has been recently found that, when spectacle frames having some types of shapes are used, the uncut lens cannot be processed in accordance with the method of attaching a lens holder at the optical center (or eyepoint). As the fashion preference of persons who wear spectacle glasses diversifies, spectacle frames having shapes of very small size in the vertical direction are occasionally used. When a spectacle frame has a vertical size smaller than a specific value and a lens holder is attached to the optical center, processing interference takes place. In other words, a portion of the outer periphery of the lens holder comes outside the shape of the spectacle frame (the shape to be formed by the processing). Therefore, the processing becomes impossible. The result is a certain range of processing interference, i.e., a range wherein a portion of the lens holder extends beyond the shape of the spectacle frame while attached to the lens so as to hinder processing of the lens. The result of this overextension (also defined herein as buildup, and more specifically lens holder completed spectacle lens buildup) is processing interference.
It is an object of the present invention therefore to provide an apparatus for and method of attaching a lens holder to an uncut lens for a spectacle lens, which enables efficient obtaining of the position for attaching a lens holder, in order to eliminate processing interference.
This object and others are achieved in a first aspect of the present invention by providing a method for attaching a lens holder to an uncut lens for a spectacle lens, comprising: (1) providing a lens holder comprising a jig operably attached to an uncut lens and defining a central axis of rotation of the uncut lens in a process for grinding an edge of the uncut lens using an apparatus for processing spectacle lenses under numerical control based on processing data including spectacle frame shape data; (2) forming an image of the uncut lens by an apparatus for image processing and obtaining the positions of hidden marks and/or position of the edge of a segment of the uncut lens by processing the formed image; (3) obtaining a position outside the range of processing interference by information processing of i) data of the positions of the hidden marks or the position of the edge of the segment, ii) the spectacle frame shape data and iii) lens holder-lens buildup area shape data using a computer; and 4) designating the obtained position as a position for attaching the lens holder to the uncut lens and attaching the lens holder at the determined position, the range of a processing interference being a range where a portion of the lens holder extends beyond the shape of the spectacle frame so as to hinder processing of the uncut lens.
This object and others are achieved in a second aspect of the present invention by providing a method for attaching a lens holder to an uncut lens for a spectacle lens, comprising: (1) providing a lens holder comprising a jig which is attached to an uncut lens and used as a central axis of rotation of the uncut lens in a process for grinding an edge of the uncut lens using an apparatus for processing spectacle lenses under numerical control based on processing data including predetermined spectacle frame shape data; (2) fixing the uncut lens to a moving stage which (i) holds the uncut lens at a fixed position, (ii) moves to a desired location in accordance with a specific control information, and (iii) measures a current moving stage position and outputs information on the position; (3) forming an image of the uncut lens by an apparatus for image processing having a reference position set at a specific position relative to a reference position of the moving stage; (4) obtaining the hidden mark positions or the position of the edge of the segment of the uncut lens by processing the formed image; (5) obtaining a position outside a range of processing interference by information processing of data including (i) the obtained positions of the hidden marks or the obtained position of the edge of the segment, ii) the predetermined spectacle frame shape data and iii) lens holder-lens buildup area shape data, using a computer; (6) designating the obtained position as a new position for attaching the lens holder to the uncut lens, (the range of a processing interference being a portion of the lens holder-lens buildup area shape that extends beyond the shape of the spectacle frame so as to hinder processing of the uncut lens); (7) moving the uncut lens to a specific position in an apparatus for attaching a lens holder by the moving stage so that the lens holder can be attached at the designated new position on the uncut lens, the reference position of the moving stage and a general position for attaching the lens holder to the uncut lens being set in a specific relation in the apparatus for attaching a lens holder; and (8) attaching the lens holder to the uncut lens by the apparatus for attaching a lens holder.
This object and others are achieved in a third aspect of the present invention by providing an apparatus for attaching a lens holder to an uncut lens for a spectacle lens, comprising: (1) a lens holder that comprises a jig and is operably attached to an uncut lens and used as a central axis of rotation of the uncut lens in a process of grinding an edge of the uncut lens using an apparatus for processing spectacle lenses under numerical control based on processing data including spectacle frame shape data wherein the uncut lens is a progressive multifocal lens having a progressively changing dioptric power or a multifocal lens having a segment integrally formed on a main lens; (2) a computer; (3) a moving stage which holds the uncut lens at a fixed position, moves to a desired location in accordance with a specific control information from the computer, measures a current moving stage position and outputs the moving stage position information to the computer; (4) an apparatus for attaching a lens holder in which a reference position of the moving stage and a position for attaching the lens holder to the uncut lens are set in a specific relation; and (5), an apparatus for image processing which has a reference position set in specific relation to a reference position of the moving stage and which forms an image of the uncut lens and obtains the hidden marks positions or the position of the edge of the segment of the uncut lens by processing the formed image based on a command information of the computer; wherein the computer operably directs (i) obtaining a position outside a range of processing interference by information processing (a) mark position data or the position of the edge of the segment, (b) the spectacle frame shape data and c) lens holder overlap area shape data and designating the obtained position as a position for attaching the lens holder to the uncut lens, (ii) movement of the uncut lens to a specific position in an apparatus for attaching a lens holder by the moving stage so that the lens holder can be attached at the position for attaching the lens holder to the uncut lens, wherein the reference position of the moving stage and the new position for attaching the lens holder in the uncut lens are set in specific relation to the specific position in the apparatus for attaching a lens holder; and (iii) attachment of the lens holder to the uncut lens by the apparatus for attaching a lens holder.
In accordance with a fourth aspect of the invention, the embodiment in accordance with the third aspect of the invention is further modified so that the progressive multifocal lens has the hidden marks placed at specific positions relative to a reference position in the uncut lens, the reference position on the uncut lens being a position predetermined by a design of a layout based on a prescription, wherein the predetermined position is a position of a geometrical center or a position of an optical center.
In accordance with a fifth aspect of the invention, the embodiment in accordance with the third aspect of the invention is further modified so that the predetermined position is a position of a geometrical center or a position of an optical center, and the multifocal lens has a segment arranged on a main lens in a manner such that a position on an edge of the segment that forms a boundary between the main lens and the segment is placed in a specific relation to a reference position on the uncut lens, the uncut lens reference position being a position predetermined by a design of a layout based on a prescription and the predetermined position is a position of a geometrical center or a position of an optical center.
In accordance with the first aspect of the present invention, it is made possible for sure attachment of the lens holder at a determined position of a lens so as to eliminate processing interference even when the spectacle frame has a very small vertical dimension. In accordance with the second and third aspects of the present invention, the lens holder can be attached to a lens without processing interference in an automatic, sure and quick manner.
Further objects, features and advantages of the present invention will become apparent from the Detailed Description of Preferred Embodiments, which follows, when considered together with the attached Drawings.